FR3046976A1 - METHOD FOR CONTROLLING THE DRIVE LINE OF A MOTOR VEHICLE COMPRISING A RECOVERY-AMPLIFICATION SYSTEM - Google Patents

Abstract

A method of controlling a vehicle having an internal combustion engine (10) and an electric machine (12) functioning as a generator and motor and an energy accumulator (18). The exhaust system (14) has a regenerable accumulator (16) which regenerates only when the engine (10) is operating in a favorable regeneration range. An operating point outside the advantageous range during a regeneration is shifted by the electric machine (12) towards the advantageous operating range. During a regeneration, the operating point is moved if the operating point which is established without offset is already in the advantageous operating range.

Description

Field of the invention

The present invention relates to a method for controlling a drive line of a motor vehicle comprising an internal combustion engine and an electric machine in the drive line functioning as a generator and as a motor and a battery accumulator. energy receiving electric energy from the electric machine and supplying power to the electric machine, the exhaust system of the internal combustion engine having a regenerable accumulator for the engine exhaust gas components internal combustion, and the regeneration occurring only when the internal combustion engine operates in a range favorable to regeneration, and an operating point located outside the advantageous operating range and at which the internal combustion engine operates, when performing a regeneration, is shifted by the operation of the machine el as a generator or as a motor to the advantageous operating range.

State of the art

Such a method is already known which relates to the control of the drive line of a motor vehicle having an internal combustion engine and an electric machine installed in the drive line and functioning as a generator and as a motor and an accumulator. electrical energy receiving electrical energy from the electrical machine or supplying it with electrical energy. The exhaust system of this internal combustion engine includes a regenerable accumulator for receiving the exhaust gas components of the internal combustion engine. Regeneration of the accumulator is only done if the internal combustion engine operates in a favorable operating range for regeneration. For regeneration, it is first operated according to an operating point outside the advantageous operating range and for the operation of the electric machine as a generator or as a motor, the machine is moved in an operating range advantageously, which is also known by the expression "offset of the point of charge". This method is also known from a control apparatus.

The system supplementing the internal combustion engine and consisting of an electric machine and an energy accumulator is also called "recovery-amplification system" because it allows in high mode, to recover energy and energy. acceleration, it provides additional torque (boost boost). Energy recovery reduces consumption and thus CO2 emissions.

The connection mentioned above with the regeneration of an exhaust gas accumulator operating with load point shift widens the operating range, allowing the advantageous implementation of regenerator.

Description and advantages of the invention

The present invention relates to a method of the type defined above characterized in that during a regeneration, the operating point is moved even if the operating point which is established without offset, is already in the advantageous operating range . The invention differs from the state of the art cited above from the point of view of the method in that the operating point is displaced during the regeneration, even if the operating point which is established in any case without offset , is already in the advantageous operating range. The invention differs from the state of the art by the characteristics developed hereinafter.

In contrast to the state of the art according to the invention, if regeneration of the regenerable accumulator is carried out and if the internal combustion engine already operates without the shift of the operating point required by the electric machine, in the advantageous range operating points, advantageous for the regeneration, it is in addition a regulation of the state of charge of the electric energy accumulator on the average state of charge.

This makes it possible to keep the operating point of the internal combustion engine more frequently within the limits required by the state of charge and longer in the advantageous operating range for the regeneration. Thus, for an average of many regenerations, the interruption of a regeneration will be rare.

These characteristics make it possible to reduce the number of stops of the regeneration because one leaves the advantageous operating range. Thus, it is advantageous to preserve this shift of the operating point already known per se, of the internal combustion engine and which is done by an intervention of the electric machine on the operating points, which are offset by the action of the electric machine towards the advantageous operating points for the regeneration.

According to a preferred development, even if the operating point of the motor is in the advantageous operating range, the state of charge of the energy accumulator will be compared to a target value. The operating point is for example defined by the amount of fuel injected per operating cycle and by combustion chamber, the rotation speed and, if appropriate, the operating characteristic variables such as the torque demand by the driver.

Preferably, the target value is between the upper limit and the lower limit of the state of charge.

According to another preferred development, the target value is in the middle between the upper limit and the lower limit.

According to another preferred characteristic, if the state of charge is lower than the target value, the electric machine operates as a generator and / or charges the energy accumulator.

Preferably, if the state of charge is equal to the target value, the electric machine does not function as a generator or as a motor.

According to another advantageous development, if the state of charge is higher than the target value, the electric machine is operated as motor so that the energy accumulator will be discharged but the state of charge will remain close to the target value. .

A preferred development of the control apparatus is characterized in that it is designed to carry out the method of the invention.

drawings

The present invention will be described in more detail below with the aid of examples of control methods of a drive line of an internal combustion engine, shown in the accompanying drawings, in which: FIG. a diagram of the technical environment of the invention in the form of a drive line of a motor vehicle comprising an internal combustion engine and an electric machine, Figure 2a is a diagram showing the torque demanded by the driver and the torque actually generated by the internal combustion engine, during a regeneration according to the state of the art, FIG. 2b shows the state of charge of an electric energy accumulator for two respective identical instants, this accumulator of energy being charged or discharged by the electric machine according to the state of the art, FIG. 3 shows a flowchart of an exemplary embodiment of the method of the invention, FIG. 4a shows the diagram of the torque desired by the driver and the torque actually generated by the internal combustion engine in the case of regeneration according to the invention, and FIG. 4b shows the state of charge of the the electric energy accumulator charged or discharged by the electric machine for each time two identical instants according to the invention.

Description of embodiments

FIG. 1 shows in detail a drive line of a motor vehicle comprising an internal combustion engine (also called a heat engine) 10 and an electric machine 12. The internal combustion engine 10 and the electric machine 12 are connected by a connection by force or by a clutch. The force connection is effected, for example, by a belt drive 13. The internal combustion engine 10 comprises an exhaust system 14 with an accumulator 16 capable of being regenerated and receiving components of the exhaust gas of the engine. Internal combustion engine 10. The regenerable accumulator 16 is preferably an NOx nitrogen oxide storage catalyst. The NOx nitrogen oxide storage catalysts accumulate the NOx nitrogen oxides of the exhaust gases over a period of the order of a few minutes and then regenerated for short phases with a rich atmosphere of exhaust gas. The duration of the regeneration phases is of the order of seconds.

The electric machine 12 operates as desired and switched as a generator or as an electric motor. The electric machine 12 is for example a pole claw machine, cooled by air, incorporating a power electronics; the machine is coupled to the internal combustion engine by a belt drive and operates at a voltage of 48 V. Such electrical machines are known.

The electrical machine 12 connected to the energy accumulator 18 functions as an electric machine 12 receiving or supplying electrical energy. The energy accumulator 18 is for example a lithium-ion battery. The energy accumulator 18 preferably has a charge state sensor 20.

The internal combustion engine 10 comprises different sensors 22 to enter operating parameters such as the speed of rotation (speed), the amount of air sucked, the temperature and the composition of the exhaust gases, this statement not being limiting. The internal combustion engine 10 comprises adjusting members 24 which make it possible to adjust the torque supplied by the internal combustion engine 10. The regulating members or actuators 24 are, for example, regulating devices which influence the degree of filling of the chambers of the engine. combustion of the internal combustion engine 10, regulators which influence the composition of the filling of the combustion chambers with air and fuel and regulating devices which influence the moment of the ignition of the fuel charge of the combustion chamber. combustion.

A control unit 26 manages the drive line by acting on the electric machine 12 and on the adjusting member 24 of the internal combustion engine, according to the indication of a program of the control device and using the signals sensors 22 connected to the control unit. For this, the signal of the state of charge detector 20 and the driver request generator 28 are applied to the control device 26 according to the torque demand of the driver. The accelerator pedal is for example the generator of the request of the driver 28. The control device 26 is designed, including programmed, to control the progress of the process of the invention and its implementation. In addition, the on-board network, which operates preferably at 48 V, consisting of the electric machine 12 and the energy accumulator 18, is connected by a DC / DC converter 30 to the on-board network 32 to 12 V so as to allow the exchange of energy between the two embedded networks.

Figure 2 shows the signal curve of the installation according to the state of the art. FIG. 2a shows the curve 34 of the torque M demanded by the driver, and the curve 36 shows the torque actually supplied by the internal combustion engine 10 over a period of time that falls within the regeneration phase of the accumulator catalyst. The value M of the pair is represented on the ordinates and the time t on the abscissa axis. The torque range of the internal combustion engine 10 which is advantageous for the regeneration of the regenerable accumulator 16 is delimited downwards by a lower limit Mu and upwards by an upper limit Mo. Within this range, it will be possible to for example, adjusting a rich exhaust gas atmosphere necessary for regeneration and a mass flow of rich exhaust gas, but not too much and setting the desired torque.

FIG. 2b shows the state of charge SoC (SoC: state of charge) of the electric energy accumulator 18 which is charged or discharged by the electric machine 12 during a state of charge which corresponds to two identical times each time, for the electric energy accumulator 18 which will be loaded or discharged by the electric machine 12 according to whether the electric machine 12 is driven by the drive line (recovery) or that it itself generates a motor torque (boost) . The state of charge of the energy accumulator 18 is influenced by the coordinated control of the internal combustion engine 10 and the electric machine 12. At time t 0, regeneration of the regenerable accumulator 16 is triggered, although the torque 34 requested by the driver is below the lower limit Mu. The torque desired by the driver is that given by the curve 34.

The torque M of the internal combustion engine 10 is raised in this case at the lower limit Mu. The torque generated by the internal combustion engine flows from the curve 36. The curves 34 and 36 are always identical if the electric machine requires no torque.

Depending on the demand of the driver 34, the internal combustion engine provides too much torque after the instant t0. This excess torque supplied by the motor then drives the electric machine 12 operating as a generator so that the load 38 of the energy accumulator 18 increases first. The charge 38 of the energy accumulator 18 must not fall below the lower limit SoC-u nor exceed the upper limit SoC-o. Between times t1 and t2, the driver's demand is in the advantageous operating range for the regeneration. In the known method, the electric machine 12 then operates again as a generator or as a motor. The charge of the energy accumulator 18 does not change.

Between times t2 and t4, the driver's demand is above the operating range which is advantageous for regeneration. In this case, the internal combustion engine 10 continues to operate to generate the torque at the upper limit Mo. The torque that fails until the wish of the driver is then generated by the electric machine 12 which now operates as a motor. The energy accumulator 18 is thus charged. At time t3, the state of charge of the energy accumulator reaches its low limit value SoC-u which must not be exceeded. In these circumstances, after time t3, the electric machine no longer functions as a motor. To generate the desired torque, and to represent it alone, it is necessary to operate the internal combustion engine above times t3 and t4 to generate only the electric motor after time t3 which no longer serves as a motor. To generate the desired torque alone, it is necessary to operate the heat engine between instants t3 and t4 above the advantageous range for the regeneration. According to the state of the art, this leads to the premature stopping of the regeneration.

In the following, it is assumed that at least at the beginning of a regeneration, one can set an operating point of the internal combustion engine, advantageous for regeneration. This is for example the first case if the driver's request corresponds to an operating point in the advantageous operating range. This is secondly also the case if the advantageous operating point for a driver request located above the advantageous range is set in operation of the electric machine as a motor, which supposes that the energy accumulator is at least not empty. This is the third and also the case if the advantageous operating point for a driver request located below the advantageous range, is set by the operation of the electric machine as a generator, which supposes at least that the accumulator energy is not complete.

Of these three cases, the present invention relates to the second case where the driver's desire corresponds to an operating point of the advantageous operating range. In the other two cases, preference is given as will be described in detail with reference to FIG.

Figure 3 shows a flow chart of an exemplary embodiment of the method of the invention. Step 100 represents the main control program of the drive line, including the engine and the electric machine. In step 102, and under the conditions given above, it is assumed that at least at the beginning of a regeneration, it is possible to set an advantageous operating point for the regeneration which triggers a regeneration or concerns an already triggered regeneration. For the regeneration of an NOx nitrogen oxide storage catalyst, the heat engine is operated to generate an exhaust gas composition in the decreasing direction. In step 104, it is checked whether the request of the driver FW (trace 34) is greater than the upper limit Mo. If this is the case, in step 106, it is checked whether at the same time the energy accumulator is not empty, i.e. if the state of charge SoC is greater than the lower limit SoC-u.

If this is not the case (the state of charge of the energy accumulator is too low), the regeneration is stopped in step 109 because the operating point of the internal combustion engine can not be moved. in the advantageous range for the regeneration between Mu and Mo. According to another development, the regeneration is stopped by a program module which takes place in the main program if the state of charge does not allow the offset of the operating point.

If the state of charge SoC is in contrast higher than the lower limit SoC-u, the electric machine 12 is operated as a motor in step 107. The torque generated by the electric machine 12 is preferably greater than or equal to the difference between the demand of the driver and the upper limit Mo. This corresponds to the situation between times t2 and t3 of FIG.

If the driver's request (curve 34) is lower than the upper limit Mo, the program derives from step 104 to step 108 in which it is checked whether the driver's request is greater than the lower threshold Mu. If this is not the case, the driver's demand is necessarily below the lower limit. If at the same time the energy accumulator is not fully charged, the electric machine 12 can be operated as a generator in step 111. In this case, the torque generated by the internal combustion engine is raised to less at the lower threshold Mu and the part of the torque generated by the internal combustion engine and which exceeds the driver's demand will be used for driving the electric machine 12 functioning as a generator to thereby charge the energy accumulator 18 In FIG. 2, this corresponds to the situation between the times t0 and t1. The torque absorbed by the electric machine 12 is preferably greater than or equal to the difference between the lower threshold Mu and the driver's demand.

For what has been described above, the flow chart of FIG. 3 is not different from the state of the art. The differences with respect to the state of the art lie in the process steps described below: if the driver's request is in the favorable range, step 108 to step 112 is the charge state SoC of the energy accumulator to a target value Z. The target value Z is preferably located between a threshold at the upper limit SoC-o and a threshold at the lower limit SoC-u of the state of charge. According to a particularly preferred development, the target value Z lies in the middle between the two limits SoC-u and SoC-o. If the state of charge is below the target value Z, the program derives in the step 114 in which the electric machine 12 operates as a generator and charges the energy accumulator 18. If on the other hand, the state of load is below the target value Z, the program goes from step 112 to step 116 in which it is checked whether the state of charge SoC is equal to the target value Z. If this is the case, the program proceeds to step 118 in which the electric machine does not function as a generator or as a motor.

If, on the other hand, in step 116, it is found that the state of charge SoC is not equal to the target value Z, the above steps show that the state of charge SoC is greater than the target value Z. In this case, the program goes from step 116 to step 120 in which the electric machine 12 operates as a motor so that the energy accumulator 18 discharges and its state of charge SoC approaches the target value Z. From steps 109, 107, 114, 118, 120 and 111, the program returns to the main program 100.

The program loop described here consisting of steps 100-120 is repeated until the end of the regeneration. The premature failure of regeneration due to unfavorable battery charge states (SoC) is largely prevented by the invention as occurs in the state of the art.

Figure 4 illustrates this advantageous effect. The chronological evolution of the FW driver demand corresponds to the chronological evolution of the demand of the driver of FIG. 2. However, differences appear in the plot of the torque generated by the internal combustion engine in the intervals t1-t8 and t4 -T5. In the interval t1-t8, the demand of the driver FW or the torque corresponding to the driver's request are within the favorable operating range for the regeneration and the state of charge SoC as shown in FIG. 4, below the average target value Z. This is a situation which corresponds to the continuation of the operations 112, 114 of the flowchart of FIG.

In contrast to the state of the art, the electric machine 12 then functions as a generator and charges the energy accumulator 18. The offset of the operating point required for this purpose in the time interval tl-t8 for the motor Internal combustion 10 develops so that the curve 36 of the torque generated by the internal combustion engine 10 is above the curve 34 of the driver's demand.

In the time interval t8-t2 following the time interval t1-t8, the state of charge SoC is equal to the target value Z. The electric machine 12 then operates according to the succession 116, 118 of FIG. , neither as engine nor as generator. In this case, the torque generated by the internal combustion engine 10 corresponds to the driver's demand.

As shown in the comparison of FIGS. 2b and 4b, the discharge of the energy accumulator 12 which occurs in the time interval t2-t4 in FIG. 4b starts from a higher state of charge. than in the object of Figure 2b. In the latter case, stopping the shift of the operating point required in the object of FIG. 2 at time t3 which also causes the undesired stopping of the regeneration phase, is a situation avoided according to FIG. .

NOMENCLATURE DBS MAIN ELEMENTS 10 Internal combustion engine / heat engine 12 Electric machine 13 Belt drive 14 Exhaust system 16 Regenerable accumulator 18 Energy accumulator 20 Energy accumulator status indicator 22 Other sensor 24 Actuator / actuator 26 Control unit 28 Driver demand generator / accelerator pedal 30 DC / DC converter 34 Driver demanded torque curve 36 Torque curve generated by the internal combustion engine 100-120 Steps of the process

Claims (9)

1 °) A method for controlling a drive line of a motor vehicle comprising an internal combustion engine (10) and an electric machine (12) in the drive line functioning as a generator and as a motor and an energy store (18) receiving electrical energy from the electric machine (12) and supplying power to the electric machine (12), the exhaust system (14) of the internal combustion engine (10) having a regenerable accumulator (16) for the exhaust components of the internal combustion engine (10), and the regeneration occurring only when the internal combustion engine (10) is operating in a favorable range; regeneration, and an operating point located outside the advantageous operating range and at which the internal combustion engine (10) operates, when performing a regeneration, is shifted by the the operation of the electric machine (12) as a generator or as a motor, to the advantageous operating range, characterized in that during a regeneration, the operating point is moved even if the operating point which is established without an offset is already found in the advantageous operating range. 2) Method according to claim 1, characterized in that if the driver's request is in the advantageous operating range, comparing the state of charge of the energy accumulator (18) with a target value. Method according to Claim 2, characterized in that the target value lies between the upper limit and the lower limit of the state of charge. 4) Method according to claim 3, characterized in that the target value is in the middle between the upper limit and the lower limit. Method according to one of Claims 2 to 4, characterized in that if the state of charge is below the target value, the electric machine (12) is operated as a generator and the accumulator is charged. energy (18). Method according to one of Claims 2 to 4, characterized in that if the state of charge is equal to the target value, the electric machine (12) is not operated either as a generator or as a motor. Method according to one of Claims 2 to 4, characterized in that if the state of charge is higher than the target value, the electric machine (12) is operated as a motor for discharging the energy accumulator. (18) and bring his state of charge closer to the target value. 8 °) control apparatus (26) for controlling the drive line of a motor vehicle having an internal combustion engine (10) and an electric machine (12) installed in the drive line and functioning as a generator or as a motor, and an energy store (18) receiving electrical energy from the electric machine (12) and delivering electrical energy to the electric machine (12), the exhaust system (14) an internal combustion engine (10) having a regenerable accumulator (16) for the exhaust components of the internal combustion engine (10), and the control apparatus (26) performing the regeneration only if the engine internal combustion engine (10) operates within an advantageous operating range for the regeneration and for regeneration, the operating point located outside the advantageous operating range for the engine is displaced. by operating the electric machine (12) as a generator or as a motor in the advantageous operating range, characterized in that during a regeneration it moves the operating point even if the operating point which is established without the displacement is already in the advantageous operating range. Control device (26) according to claim 8, characterized in that it controls the method according to one of claims 2 to 7 if the driver's request is in the advantageous operating range, and the state of charge of the energy accumulator (18) at a target value.